Cooling fan 98' 2.4L

[Katie2702]

My cooling fan will not come on

My engine will start inching up towards the red line and it still will not come on. Can someone help me out?

[rodfoster]

These fan are known to seize up, but also you need to make sure there is power going to it, and that it is being told to come on when it should.

[J-Ri]

Get a test light and connect the clip side to B+, then probe both contacts in the fan connector. One should light it up. Then switch the clip to B- and probe the other terminal with the temp gauge about 3/4 of the way up and the engine running. The other terminal should light it up. If you get the light on both times, then the fan motor is bad. Otherwise you'll need to do more testing.

EDIT: I just saw the post you made in that parts thread. The cooling fan is an extreemely common problem, so chances are a used one will go bad soon. One part that you definately want to buy new. They're not very much anyway, around $30.

[gearhead514.2008]

I have a Cavalier with the same problem. These cars are notorious for cooling fan problems. I think the problem is with the powertrain control module or the wiring to the fan relay from the module. The test on the above reply is a good test, but there is another way to find out if your fan is working. Find the cooling fan relay in the electrical fuse panel under your hood on the right hand side. Remove the cooling fan relay and use a little screwdriver to remove the square plastic cover on the relay. Now you should see the internal contacts of the relay. Plug the relay back into the socket without touching any of the exposed wiring. Now, you must manually push the plastic part of the contact tips closed with a screwdriver or something. The fan should turn on. If the fan does not turn on, you should check the fuse and the power coming into the relay. If the fan does come on, then your relay is not getting the signal from the powertrain control module to actuate. This relay is wired a little different than normal relay wiring methods. If you know how a relay works, it is basically a switch that is turned on and off by a magnetic solenoid. This solenoid is energized by electricity to create the magnetic pull to close the power contacts for the fan to run. When I say this relay is different, I mean the positive +12V side of the solenoid is connected all the time to the battery positive. The negative(ground) side is given a ground by the powertrain control module. This is reverse of normal wiring schemes. The powertrain control module in these cars are somehow not giving the negative(ground) to the solenoid for your fan relay. If you use a jumper wire and connect one end to ground and the other end to the negative side of the solenoid, then your fan will turn on. You are basically bypassing the Powertrain Control Module. This is what I did to my car. Instead of replacing the PCM or troubleshooting the wiring harness, I bought a round switch and put it into my dash where the cigarette lighter was and used the cigarette lighter ground wire for my source. I hooked up the cigarette lighter ground wire to one side of the switch. Next, I ran a wire from the other side of this new switch to the engine compartment and connected it to the negative(ground) side of the coooling fan relay solenoid under the electrical fuse box. I am now able to control my fan with a switch. As long as you can remember to shut it off when you turn your car off as it will drain the battery. If you are really good with relays, you can add a relay to switch the ground on and off with the ignition switch. Sorry if I get a bit technical. I don't know what your background is, but if you get a wiring schematic and have some electrical control knowledge, you can make a car do what you want it to. Computers are great, but when something stops working, sometimes it is cheaper to go old school. Hopefully this helps. If you have any more questions, let me know.

[J-Ri]

The reason I test it like that is because most often the fan is what's bad. After bypassing the relay, if the fan still doesn't come on, you have to check for power and ground at the fan anyway to rule out a bad wire or ground.

Many newer cars use a negative control on the relay. The reason behind this is that when the coil is turned off, the magnetic field collapses and induces a voltage spike (like a miniature ignition coil). If the spike goes to the power side, there's no problem. If the spike goes to ground, it temporarily reverses the polarity of any other relays that share that ground, which results in two very short (mS) periods where there is no current flowing through the coils. This is made worse when the ground gets corroded, and can get to where the relay actually turns off for a bit when any other relay is de-energized.

On your car, Gearhead, I would guess the ECT sensor is probably bad. The gauge sender and PCM sensor are two different circuits. Most people think that the fans come on when the gauge gets high... while that's true if both circuits are functioning correctly, if the ECT reads -40 degrees (shorted sensor), then the fan will never come on. In almost 6 years of diagnosing electrical problems, I have only seen one PCM with a bad driver. Not saying they can't or don't go bad, just that you may have an easy fix for your problem, if you don't like having to switch it on and off manually

[gearhead514.2008]

Thats cool. I was just wondering that if they didn't have a test light or multimeter, that is an easy way to check and see if it is a power problem or a control circuit problem. As for my cavalier, I never received a code for a malfunctioning ECT sensor on my scan tool. I have had this problem on my Pontiac Montana where the ECT sensor is shorted and it shows -40 degrees and throws a code. I have checked my Cavalier for codes and have not found any for the ECT sensor, however, I have not checked the actual temperature reading yet. I will have to go out there and view the live data on my scan tool and see what the actual temperature is. The code I am getting is for a cooling fan control circuit malfunction. I have checked the power side and the control side, but my PCM is not supplying the ground to energize the coil. The car is a piece of junk anyways, so I just hotwired it with a switch. Anyways, thanks for the info.

[Katie2702]

Thanks for the replys. I'm going to get my friend to try the tests you gave me and I'll let you know what's wrong with it.